Why No Comma
In Dow 10000?

Even before Monday's milestone, some readers have wondered why The Wall Street Journal refers to Dow 10000, not 10,000 with a comma.

Well, the Journal's traditional style is to express index values without commas separating every three digits, just as is done with dates (1999, not 1,999). Among other reasons, it is easier to list index values in tabular material this way. This is also the way that the five-digit Nikkei and Wilshire...